text:
What are the ways to perform air traffic control on long distance flights?
I have a few questions on air traffic control.
From my understanding, there are three major ways of sending control messages to an aircraft:
1) Direct radio link from control as long as the aircraft is in the line of sight.
2) Satellite
3) Ground stations, e.g., TRACON.
My questions are:
a) For an intercontinental flight, how does the control know which ground station to use (since it wouldn't make sense to connect all ground stations to each airport) for control messages?
b) Are the control links (e.g., control-to-ground-station-to-aircraft) to communicate with an aircraft predetermined before take-off?

Don't you think this is a bit too much for a site that aims to answer one question only per post? Please consider reformatting the question.

I reformatted my questions. Thanks.

Your question seems confusing, are you talking about ATC (and how aircraft are handled within a certain airspace) or controlling the aircraft using remote means?

I'm taking about ATC.

Question a) is, essentially, "How does cellular communication work?", which isn't a question about aviation.

@mins "Which groundstation should I use to communicate with a moving object?" is exactly a question about cellular communications. I'm talking in the general sense, not restricting to handheld mobile telephones. It seems to be based on the misconception that ATC would want to talk to planes that are far, far away and therefore need to know what radio transmitters it's in range of, but the question itself is laid out as one about cellular communication.

Direct link vs satellite

There are three major ways of sending control messages to an aircraft:
  Direct radio link [when] in line of sight, satellite, ground stations,
  e.g., tracon.

The way the question starts brings confusion so the many comments. There are two categories of radio links involved in voice/data communication: Between a ground station and the aircraft and via a relay, e.g. a satellite.

Satellites are merely used today for air traffic control, it's a thing of the future (2 to 3 years for tracking the aircraft using ADS-B). However satellites are sometimes used for aircraft communication with the airline technical staff and/or the manufacturers. However the information exchanged here is not ATC related at all: It can be technical, e.g. live ACARS sent to airline technical staff or to the engine manufacturer, to prepare maintenance at the destination airport. It can also be internal exchange with the airline operations. Satellite communication is also used for passenger services like telephone and Internet access aboard the aircraft.
So ATC uses the other kind of links, the direct ones, which means a transmitter on the ground. However these "ground stations" can serve different purposes because ATC is organized so that ATC facilities are specialized.

Simple ATC organization
There are ATCOs on the site who may add details to this answer, but I'll draw the mainlines. In the US, ATC operational facilities are divided into 4 categories:

ATC Tower. Controllers are located in the airfield tower and they control aircraft on the ground (e.g. at their gates, or on the taxiways), aircraft on the runways (landing or taking off), aircraft approaching the airfield to land, aircraft leaving the airfield and climbing to their cruise altitude. The tower controllers have a good sight on all those aircraft.
Tracon (terminal radar approach control). Controllers maybe located in the tower or at other locations. They are in charge of taking over the aircraft that just took off and are now departing. They continue the control that was started by their colleagues of the Tower. They also take care of the descending aircraft before they are handed over to their colleagues of the Tower for landing. As you see, tracon actually takes aircraft from cruise altitude to near the landing runway, and from near the takeoff runway to cruise altitude.
Next, there is the enroute ATC center for controlling aircraft in cruise, between the departing tracon and the arrival tracon. This facility is also known as air route traffic control center (ARTCC). The enroute controllers can be located anywhere, they don't need to see the sky, and usually they don't see it at all, they work in a dark room using only displays and microphones. There are a small number of centers in the US to control the whole US airspace.

This split is shown on this figure:

that is extracted from this question.

The last type of ATC facility is the oceanic ATC which controls an ocean area, because the procedures and tools used are a bit particular. Oceans are not belonging to a particular country, however all countries have agreed to delegate the control to a particular country for a particular area. In the US, for the East coast, New-York oceanic center will control an area, Canada will control another, UK and France will manage the other side of the pond. These centers control areas named OCA, for oceanic control area. See this map for North Atlantic. When the aircraft progress along its route, it is handed over to the next area controller.

This was the first part: We have clarified who are the controllers and ATC facilities, where they are and what phase of flight they control. Now let's see the radio equipment they use.
Radio links
First let's clarify between radio and radar.

Radar is used to determine the position of the aircraft. This can be done everywhere, except over oceans. The reason is radar has a limited range, and there are no radar stations in the ocean (at least not for civil aviation).
Radar stations are located at selected locations, on hills and other high places, to increase their range. some radar are located on airfields too, but that's not a requirement. Actually, all information collected by all radar stations are gathered and distributed to all control centers as a synthetic picture.
Radio is used to exchange voice messages and data. As I wrote, all radio links have a ground station at the center. This ground station is usually at the same location than the controllers. So some ATC radio equipment is at the airfield, some at the enroute centers, etc. For OCA, the equipment can be remote from the controllers, but this is just a technical detail.

Aviation radio for ATC messages can use two types of frequencies:

VHF (very high frequency) which works mostly in line of sight, so the range is something around 50 km to 200 km depending on propagation conditions and location. VHF is used when the aircraft is flying over lands. Controllers at the towers and tracons use VHF, as they deal with aircraft that are either under they eyes (tower) or at a moderate distance from the airfield (tracon). Enroute use them too as they control the part of the sky around the transmitter.
HF (high frequency) works on long distance, like between continents. HF is used by OCA controllers, enroute ATC can also use them. The particularity of HF links is they work somehow erratically, the links can be broken at any time when an aircraft flies over an ocean. The reason is HF waves are reflected by the high ionized atmosphere and the ground, but the degree of ionization varies with time. OCA facilities have procedures to deal with that.
A special word on ATC communication in OCA: Satellites are not used by ATC today. In OCA, ATC communicates with aircraft using HF transmitters located on the ground. When the distance or propagation conditions make the HF communication impossible, ATC (or the aircraft crew) will ask another aircraft to relay the message. Aircraft equipped with satellite phone can also try to contact the OCA center using telephone. If communication is still impossible, then the crew will continue as already cleared by ATC, and after they will continue as indicated in the flight plan which was filed with ATC before the flight. ATC will clear enough airspace around the assumed position of the aircraft to prevent collisions. This is not very different than when there is a loss of communication over land. See section Communications Failure After Entering NAT Region at the end of this document (NAT is the standard North Atlantic route system often used to cross the Atlantic Ocean).

For an intercontinental flight, how does the control know which ground
  station to use (since it wouldn't make sense to connect all ground
  stations to each airport) for control messages?

I hope you have got a better understanding, and know now this is not the case. Each ATC facility (tower, tracon, enroute center) uses different radio stations and a particular tower controls only the aircraft at this airport, using the local transmitter. The key is that ATC works with pre-agreed procedures to hand off control to the next facility when the aircraft leaves a given control area. An ATC unit controls aircraft in its area, and uses a ground radio station nearby the aircraft. OCA ATC indeed works with aircraft that are remote, and sometimes very far.

Are the control links (e.g., control-to-ground-station-to-aircraft) to
  communicate with an aircraft predetermined before take-off?

Yes they are, not on a paper, but by the procedures. When the aircraft starts its engines, the crew is in contact with the "ground controller" who is a controller in the tower, specialized in controlling aircraft which aren't on the runways. When the aircraft is ready for takeoff, the ground controller hands over to someone else in the tower who manages the takeoffs (this is "the tower controller"), then after take off the tower hands over to the nearby tracon, then to enroute (there will be several successive enroute centers), etc.
The current controller hands over to the next controller on the aircraft route, when the aircraft is leaving their area of responsibility, this is part of the ATC organization itself.
"Plates" used by crew indicate how to reach a given control facility. For example, on this chart, the frequency of the Denver ARTCC is mentioned explicitly.

Source
This is in case you are lost because this information is normally given by the previous controller prior to handing you over to Denver enroute center:
And here is how to contact the different ATC units at Paris - Charles De Gaulle:

Source

More: ATC Facilities

For Oceanic flights, do they use satellite to send ATC at all (or just aircraft-to-aircraft radio links)? What if there are no nearby aircraft or other ATC facilities?

Satellites are not used by ATC today. In OCA. ATC communicates with aircraft using HF transmitters located on the ground. When the distance or propagation conditions make the HF communication impossible, ATC will ask another aircraft to relay the message. Aircraft equipped with satellite phone can also try to contact the OCA center using telephone. See section Communications Failure After Entering NAT Region at the end of this document (NAT = standard North Atlantic route system)


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Do pilots need a clearance to go around?
I have read about the missed-SFO-accident and watched the 2:22 movie. I want to ask about going-around (or canceling takeoff) when the pilot is fully aware of an emergency that the tower is not (or is late at acting).
According to the reconstruction of the real missed-accident done by the news:

Air Canada pilot was on final cleared to land, but instead heading to taxiway for reason that will be explained after FAA & TSB investigations
Tower did not notice and did not complain, clearance was still ok
Pilot double-checked with tower because he saw lights on the ground
Tower double-confirmed clear to land
Other pilot on queue said "where is this guy going?"
Tower requested go around
Air Canada flight crew initiated go around.

The order of the last two events is currently not clear and subject to investigation.
In the movie both ingoing and outgoing pilots are scared by the sight of each other but ATC Dylan doesn't command action until the last moment, while clearance to land and take off is still granted for both.
It is clear that in the movie ATC has failed and pilot(s) are aware of a real danger that affects the safety of flight operation.
Like a driver sighting an animal on the road and braking (or worse moosing) without calling the police first. I am no pilot, I understand that flight is definitely different from driving. And I also enjoyed my time on MSFS virtual flight school. I said the above because I know it could be disappointing for experienced pilots.
I want to ask for my culture/curiosity: when a pilot is cleared to takeoff/land but sees a legitimate reason to cancel the maneuver (e.g. stop/go around), can he simply advise the tower that he is doing that or must continue as earlier instructed? AFAIK when an indicator indicates failiure at < 80kt speed the pilot can immediately cancel takeoff, otherwise is required to continue.
My idea is that the Air Canada pilot could have told the tower something like "we are now fully thrusting and going around because I am not sure about the safety of this landing, please give me further instructions for looping" by his initiative.
This is allowed in the MSFS simulation (you can open virtual ATC radio and announce missed approach even a few feet above ground, they will tell you how to loop over the circuit asap). Is it allowed in reality, or do pilots need a clearance to go around?

What makes you say ATC failed? The pilot lined up for a taxiway instead of the runway, that's not exactly the towers fault.

As far as I know, it is not clear weather the pilot initiated a go-around before of after the ATC instruction, this is subject to investigation.
Also I don't see from the evidence currently available that ATC has failed as you say. It is the responsibility of the pilot to line up for the correct runway.

I used italic intentionally. Well, in the movie scenario the tower definitely failed because they cleared both planes on crossing runways. As for the SFO incident, it depends on whether it is tower's duty and technical possibility to proactively tell the pilot that he is out of route. It is just my personal impression that the tower acted late after getting feedback from other planes. Rightfully: could they act earlier? Did they have to? [EDIT] Anyway I can rephrase

@J. Hougaard:  By the pilot's last radio call, he clearly thought something was wrong, and asked ATC for clarification.  Although the primary responsibility is with the Flight Crew, ATC had a clear opportunity to assist, and failed to do so.  I'd say that controller was not operating at 100% on that particular call.

Please note that questions about accidents (or even near accidents) where an investigation is on-going are not allowed to be asked (directly about the specifics of the accident). In this case, it would seem you have asked a generalized enough question to remain on topic, so well done.

And do not forget I have compared the real accident with a fictional accident depicted in a film

@DeltaLima According to Avherald, they had already overflown the other traffic just before Tower called the go-around.

@reirab If Avherald is correct, that would be an indication that the pilots initiated a go-around before instructed to do so by ATC.

@DeltaLima Correct.

ATC communication: https://www.youtube.com/watch?v=ZW-ETmZU0u8

@abelenky: Can an Air Traffic Controller, staring at several screens inside the tower, tell if an approaching airliner is aligned to runway or a taxiway, when the separation between the two is just around 100 meter mark? I doubt that.

@Krumia:  Tower has a lot more than screens, which is precisely why they're in a tall tower with big windows. Most tower controllers have a 360° view. Whether or not they were in a position to see precise alignment from that particular tower at that particular airport is a matter for the investigation, but it is a distinct possibility.

No, and this applies to any pilot, not just an airliner pilot. After the pilot has been cleared to land (or even if you're landing at your own discretion at an untowered airport), he can decide to go around instead of landing if he's dissatisfied with the approach for any reason.
The pilot might need to abort the landing for reasons the tower can't possibly know about, such as a gear unsafe indication, failing to achieve a stabilised approach, not making visual contact with the runway, or some distraction within the cockpit. And even in the case of a reason the tower should be able to tell - such as another aircraft infringing the runway, lining up on the wrong runway by accident, or birds on short final - the pilot must still go around if he thinks it's not safe to land, without waiting to be told.
The same applies to taking off. Even after being cleared to take off, the pilot must not take off if he thinks it is not safe to do so, even if it's for a reason the tower should know about, such as a runway obstruction or a take-off clearance on a crossing runway.

I usually think of it like this "Cleared to land" means your allowed to land, not that you must. In fact all airport diagrams that I have seen have a "go around" "path" on them, with instructions on how to wait to be re-inserted in the "landing queue". Same with "Cleared for Takeoff", you don't have to take off, you can just sit there for 45 mins. That's pretty rude, and I'm sure it will cause other issues. But the clearance only means you can, not that you have to.

@coteyr If you try to sit there for 45 minutes you'll certainly be asked to vacate the runway! And on the "diagrams" you've seen you've noticed the missed approach procedure, which is for instrument traffic only: it's designed to assure terrain clearance even if you can't see anything on the climb-out.

@DanHulme Of course you will be "asked" to clear the runway, but if you need a tow truck and a fire crew to do that safely, you are quite entitled to ask for them and stay where you are! A request is not a command. ATC isn't in command of the plane - you are.

@alephzero That is a very different situation. Nothing rude here.

The pilot of an aircraft is responsible for the safety of the flight. If he wants to go around or cancel takeoff, he can and will just do so. The purpose of ATC is to provide a service to help the pilots, not to tell them how to do their job. More technically speaking, when a flight is cleared for an approach, they are also automatically cleared to fly the associated missed approach.
The Air Canada pilot did not notice he was lined up for a taxiway before the pilot on the ground said so. Because the taxiway is parallel to the runway, this would have been very hard to see from the tower. The tower did nothing wrong, since they cleared the flight to land on the empty runway. It's hard to say why the pilot lined up for the taxiway instead.

Of course. It will be the investigator's duty to clarify

This is a great point - the pilot is the one responsible for all of the things.

I can buy that the offset might be hard to distinguish visually, but wouldn't it be clearer on a radar screen?

@E.P. Not when the runway and taxiway are so close and exactly parallel.

If a pilot decides to go-around for any reason, he can intiate a missed approach without making any radio call.
There is a good reason for this. The decision will usually be made late in the approach, either because the decision height has been reached without visual contact, the approach has become unstable, or some other safety issue has arisen. All these situations require immediate action by the flight crew. However, it may not be possible to contact ATC at this point. The frequency may blocked by other people speaking or the pilot may simply be too busy to make the call until his aircraft is safely established in the climb.
That is why there is a standard missed-approach procedure specific to each individual runway at major airports. This will have been designed to ensure separation from other traffic should a go around be required. In multi-crew operations the pilots will have briefed the missed-approach procedure before arrival, so both will have a clear understanding of what needs to happen without having to scrabble around the approach charts. For example, the standard missed approach might require a straight-ahead climb to 3,000ft and then a right turn to take up the hold over a navigation beacon.
If ATC sees that the aircraft is going around before a radio call is made (as is often the case) they know the crew will carry out the standard missed approach procedure unless advised otherwise. The crew will then call at the first opportunity to confirm the go around and give their intentions.

Exactly like when I sim-fly over major airports. Charts report the decision height and the climb required for a missed approach

On the flip side, would towers be expected to withhold landing clearance any time the go-around path was not clear, so that clearance to land would always imply that both paths were clear?

@supercat You should ask that as a new question, so that everyone can see it and answer. (The short answer is yes, but there are special cases.)

A pilot does not need to get clearance for a go-around. Seconds can make the difference between safety and disaster, once a pilot recognizes a situation where a go-around is required they are expected to initiate the maneuver immediately. Once the pilot has established a positive rate of climb and followed the immediate go-around actions they will then contact ATC and inform them they have gone around.

A clearance gives the pilot permission to do it, but the pilot is not required to do it. Moreover, a go-around, or missed approach, can be executed at the pilot's discretion whenever he or she is not comfortable about anything.
I have some flying experience myself and I have executed go-arounds for all kinds of reasons, some not serious at all. I have also aborted takeoffs before for several reasons. In neither of these cases did I ever request permission. The general rule is "if in doubt, go around."
A pilot tells ATC that he or she is executing a missed approach (only after you have dealt with more serious matters), they don't ask for permission.
On approach to land, the crew usually also prepares to go around, just in case they need to. Pilots study the missed approach procedures for an airport and are ready to execute them whenever needed.
Furthermore, a pilot can disobey an ATC instruction, if obeying the instruction would jeopardise the safety of the flight.

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What is the reference point for AGL?
I am about to start my PPL soon (still flying in FSX) and I do not understand one thing. As per FAR 91.159 if my altitude is above 3000' AGL I must maintain certain altitude depending on my course, BUT what would be my reference point to know that I am above 3000' AGL? Departing airport? MEF from chart? or just look out my window? Thanks!

Find the highest point near you on the chart (building or mountain), add 3000 ft to its elevation and stay above that.

AGL means above the point you are flying over, hence this is an irregular surface parallel to the ground, measured using a barometer. But you don't know the local QNH in general, so you can use the regional QNH or the QNH of the highest point in the area.

As far as I know AGL really means AGL and not as measured from the highest point in the grid.  Unless you are flying in an area where ground height varies a few thousand feet in a few miles, you will be fine with the altitude of the departing airport or the contour colors as depicted in the sectional.

I use ForeFlight to let me know my AGL altitude. You can display your current AGL and, with the profile view, the AGL on the route. Before I started using ForeFlight, if I was not sure of the height of the terrain I was going to fly over, I’d use my Garmin GPS to toggle over the map. And before that, just guess based on the chart, nearby reference points, and the contours.

On bigger aircraft there's a radar altimeter that gives you precisely that (AGL). Typically the radar altimeter reading is only shown when below 2500ft or something similar.
In little planes you don't have that information.
You estimate.
Using a sectional chart the MEFs are one way to go, but we should think about what the AGL figure is meant for.
For instance MEFs will include buildings, towers, anything that raises obstructions to flight.
But that's not AGL. AGL would be above the ground.
For instance there are rules on maximum speed near airports up to a certain altitude. For that I would use the airport elevation, since its meant to produce a veil around the airport with a fixed height. AGL is used to make it clear that you are not looking for MSL altitude.
If its something to do with terrain clearance then MEF for VFR and MSA for IFR flight is clearly the best option.
And there's the rule about separation from ground objects. Those are to be estimated visually and given a wide berth !

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What if a aerobatic fighter pilot sneezes in middle of a maneuver?
No offense to any pilots, I am a student, curious.
I just watched Spy (2015) and I was just wondering what happens if one of the pilot accidentally sneezes during a difficult maneuver.

Jude Law misfires during a critical stand-off.
I mean what are the preventive measures taken to avoid this - the jet is obviously primed to be in best of its agility & stick-sensitiveness so can the pilots selectively decrease sensitivity of stick when needed?

What happens if a football quarterback sneezes during a play? Or if a racecar driver sneezes during a race? How often does any of this happen?  Somewhere between "very rarely" and "roughly never."

Stay focused and don't tense up.  Snot in your mask. Barf down your front. Sweat. Glare. Squeeze. Hot & Cold like an astronaut in space. Focus, focus, focus. And relax.

I don't think the scene is realistic. I suspect it can't happen in reality. The reflex is somewhat controllable and I believe also suppressed in such situations (so is itching and even pain).

@JanHudec: I believe so, too. During high-stress situations, our systems are flooded with adrenaline, cortisol, norepinephrine, various endorphins and a lot of other wonderful substances that any street dealer would be proud of. You simply don't sneeze during stress.

More information required.  How "wet' is the sneeze?

Look up "photic sneeze reflex" it is a documented risk factor. Like height, eyesight, Gs, etc there's not much you can do to change this. The preventive measure is they rule you out from becoming a pilot.

Evolution has created this wonderful thing called stress. We tend to think of stress as something negative that is to be avoided, and that is certainly true: prolonged periods of stress will do all sorts of damage to your body and mind.
However, for short periods of time, stress is a wonderful invention that lets us survive situations we otherwise wouldn't: when we come under stress, when that sabre-tooth tiger pops out from behind the bushes, our autonomous systems produce anti-inflammatory agents, dampen our pain reception, flood our system with performance enhancing drugs, improve our perception, shorten our reflexes, increase our energy levels … and, yes, also repress our sneeze and cough reflexes.
Have you ever had the experience that, after a long period of stress, just when you were finally looking forward to some well-deserved vacation, you get sick at the most inopportune time, right at the beginning of your vacation? Well, actually, you didn't get sick, you were sick all along, but during the stress period, your body suppressed the symptoms, and as soon as the stress goes away, the illness, wich may have been brewing for days or even weeks, breaks out in full.
So, to answer your question:

What if a aerobatic fighter pilot sneezes in middle of a maneuver?

He doesn't. Stress will prevent him from doing so.

stress prevents sneezing, really???

@Jpe61: Yes. Adrenaline suppresses sneezing and coughing, among all the other cool things it does, like increasing blood flow, increasing oxygen flow, heightening senses and reflexes. Ever seen a theater or musical actor sneeze? I myself had the experience that I was recording songs while having a horrible cold. I had trouble breathing and had to sneeze every couple of seconds. And yet, as soon as the recording room door closed, my sinuses cleared up, and I didn't sneeze once while the red light was one. I lrecorded 3, 4, 5 minute songs and the second the red light went on, the "sneeze" …

… sensation was gone, I felt totally fine for the duration of the song, and as soon as the red light went off at the end of the song, I had to sneeze as if my life depended on it. But I never had to hold anything in. I just simply didn't need to sneeze while the tape was rolling. I was literally practicing the exact same song, plagued by constant sneezing, then hit the record button and playing the entire song without any interruptions as if I was completely healthy.

I was kind of looking for a reference to a scientific study.

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Can a "Destroyed" Helicopter be repaired and flown?
If a helicopter is reported by the NTSB as Destroyed in their Accident report, and as they make no disposal recommendation in their reports, can the aircraft be legally rebuilt by an authorized and approved FAA and Bell Repair facility and flown again?

Follow up:
The aircraft in question, after using Bell referenced repairs, carried out by a Bell Licensed Repair facility, in a Bell Certified Jig, now has its Certificate of Airworthiness and is again Supported by Bell and has a handsome price tag.

Is that a question with a specific case in mind? Could you consider adding a reference to the investigation report?

As for cars insurance, a good question is the cost of repairs compared to the cost of the helicopter before the crash.

The NTSB defines Destroyed as

Damaged due to impact, fire, or in-flight failures to an extent not economically repairable.

Another common definition is:

The estimated or likely cost of repairs would have exceeded 50
  percent of the new value of the airplane had it still been in
  production at the time of the accident.

This fact that the costs of repairing are estimated to be exceed the economical value of the aircraft does technically not prevent the aircraft to be repaired and made flyable again. It can be recertified on the original airworthiness certificate. See FAA order 8130.2H.
Special attention needs to be given to the identification plate (serial numbers etc.) of the aircraft; the original plates of the aircraft have to be installed.
Do not expect any support from Bell as on their website they state:

There are some aircraft that have been destroyed in an accident or
  retired from service that are no longer considered to be genuine Bell
  Helicopter Aircraft. These aircraft will not be supported by Bell
  Helicopter.

This makes resurrected Bell helicopters very difficult to sell in the future.

Difficult to sell, perhaps, but it seems that one could actually rebuild it and get it certified for flight again. Since it's been written off, this would likely cost more than one could get in an attempt to resell it, so it would be done out of love or insanity, and, therefore, resale value probably isn't an important issue for one doing so.

Any aircraft or helicopter listed as Destroyed by either the FAA or NTSB or both, cannot be rebuilt.  Check the FAR's.

If this is correct, we would prefer an answer that cites the relevant FAR's as the previous answer does.

It can be done with written approval from the FAA.  Read paragraph 207.d. of Order 8130.2H.  There is of course, no guarantee that approval will be granted, but it is possible.


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Is there a difference between "aerobatic" and "acrobatic" flight?
I hear and read both the terms "aerobatic" and "acrobatic" used to describe the more extreme maneuvers such as spins, rolls, loops and more. My questions is about the terms themselves. It seems that they are interchangeable, but is one actually more correct to use than the other? Why do we have these two very similar words in the aviation vernacular that seem to mean the same thing?

I'm voting to close this question as off-topic because I feel this is more appropiate to English.SE. This is interesting question though.

If there is a good aviation definition, or even a regulatory definition, that should be on topic here. On that note, this question is related.

"acrobatic flight" is when you perform hand-stands, cartwheels, etc. in the passenger cabin during flight. "aerobatic flight" is when you perform rolls, loops, and other such interesting maneuvers.

@reirab Haha please post that as an actual answer. I'd upvote.

How about if a wing-suit flyer does rolls and somersaults in flight?  Is that acro- or aero- batics?

Acrobatic is being incorrectly used, although it is slightly more complicated than that.
"Aerobatic" refers specifically to flight, and "acrobatic" refers specifically to feats of the human body, so referring to an aircraft as performing acrobatics is wrong.
That said, the word "aerobatic" is derived from "aero-acrobatics" and sounds nearly identical, so it's an understandable and relatively common error.

So, wingwalking is acrobatics, a looping is aerobatics. Got it. So, what's wingwalking during a looping? :-D

@JörgWMittag that would be: aerobatical acrobatics!

@JörgWMittag a form of insanity.

[Citation needed] for the claim that "acrobatic" refers specifically to the human body. In particular, you're claiming that the etymology of "aerobatics" is an oxymoron: if "acrobatics" can only be done with the human body, then "aero-acrobatics" is a contradiction in terms. If "acrobatic" could refer to something done by a plane before the word "aerobatics" was coined, why can't it refer to that, today?

The Oxford English Dictionary's etymology for "aerobatics" is "After acrobatics" and defines it as:

Feats of expert aviation, performed esp. for display. Hence aeroˈbatic a.; ˈaerobat, one who performs aerobatics; hence as v. intr., to perform aerobatics; also trans.

So it's a new word pertaining to aviation based on one for (also Oxford English Dictionary):

A rope-dancer; a performer of daring gymnastic feats and evolutions; a tumbler. lit. and fig.

Edit: Notice the fig. at the end of the definition (which is an abbreviation for figuratively).  So "acrobatic" can correctly be used to describe a person, cat, airplane, etc... performing "acrobatics".

Some of the other answers seem to claim that acrobatics would be incorrect when used to describe aerobatics, however when you look up various definitions you will find out that

acrobatics : difficult and dangerous acts done by an acrobat; also : difficult or dangerous acts, movements, etc., done by another kind of performer

Source: http://www.merriam-webster.com/dictionary/acrobatics
So, acrobatics is just the generic word, whilst aerobatics is the more specific word describing a very specific form of acrobatics: acrobatics in the air flowing from the following etymology:

aer- + acrobatics => aerobatics

Source: http://www.merriam-webster.com/dictionary/aerobatics
So in conclusion it's fine to use either term, especially when it's already clear that the context is about aviation. In an undefined context it might however be useful to have two words, for example

I went to an aerobatics display

and

I went to an acrobatics display

of course hold two very different meanings. Point is just: If you can pick, pick aerobatics, but don't go correcting people who aren't saying anything wrong.

In my opinion, acrobatic is more related to a person, "One who is skilled in feats of balance and agility in gymnastics".
However, aerobatic relates to maneuvers on the air.

“Aerobatics” is only a portmanteau of “Aeronatical Acrobatics” either is fine and anyone who corrects you is a word snob.

This doesn't add anything to the existing answers.


text:
How is the central hub / shaft casing of a two-spool jet engine assembled?
This is the usual view of a two-spool turbine engine:

(From source)
I don't know if shaft casing or hub are correct names, this is the external skin of the volume around the N1/N2 shafts.
I can't find a description of how this volume is made. It seems descriptions omit a number of elements for simplicity, for instance, this drawing from this answer:

(Source)
My interest is about the green area. It's not clear to me:

How airtightness is obtained overall on both sides of the core air duct?
How airtightness is obtained in locations like 1, 4 or 5 when rotating elements meet stationary (or N1) elements?
How torque is transmitted from the HP turbine to blade 2? or how elements (like 3) between the turbine and the compressor discs are assembled together to form a rigid wall/pipe?
How stators (like in 3) are fixed?
Why the central hole size varies for the rotor discs (like 2)?

Cross-sections would help but I can't find ones.
Bottom line: Without necessarily entering into details (but they are welcome), could you provide an overall description of how this "hub" is assembled, particularly the HP part?

The first thing to know when designing jet engines, is everything leaks. But the OD of the engine core is generally pretty tight. This is achieved using large solid structural pieces, for example the entire LPT outter casing is generally one piece. These large pieces are bolted together with an excessive number of bolts to make them very tight. Any penetrations will have various types of seals and gaskets, as well as high clamping forces. Although the outer case is pretty tight, the cavity between the core case and the bypass duct is still actively purged with air from the low pressure compressor (labelled as undercowl cooling on the image below).
GE90 Engine Airflow Diagram (This is actually a widely available training poster but I stole it from here, you can find similar for just about every engine)

As for the inner side of the core, this is where literally everything leaks. As you can see in the picture above, Stage 1 (S1) High Pressure Compressor (HPC) bleed air is used to actively purge the cavity under the Low Pressure Compressor (LPC) and early stages of the HPC. It is then plumbed though a small duct around the low pressure shaft to the Low Pressure Turbine (LPT) (zoom in on the image and flow the arrows in the yellow fill).
Your location number 1 is the split between the LPC rotors (spinning) and the Fan Frame (stationary). Your location number 5 is the split between the LPT (spinning) and the turbine rear frame (stationary). In these locations (and in all gaps in the ID of the core) the air is allowed to flow back into the flow path. The purge air must be at a higher pressure the flow path air, and allowing it to flow back into the main flow path actively purges these gaps and in the turbine prevents hotter gas path air from backflowing into the rotor cavity.
Your location 4 is at the end of the compressor and beginning of the combustor and is known as Compressor Discharge Pressure (CDP) air. The image below (source) shows what is going on here. A faction of the air is directed directly into the combustor through the fuel nozzle assembly, while the rest bypasses and is used as dilution air, as well as combustor liner cooling. Another faction is taken off the OD to cool the S1 HPT Vane and Shroud, while a larger fraction is taken off the ID to cool the S1 HPT Vane, Blade and rotor, as well as actively purge the gap between the S1 blade and vane. If this cooling air was ever lost, the HPT would literally oxidize/melt/creep away in a matter of seconds. The gap at location 4 is sized so the correct about of flow goes into the combustor dome and the right amount bypasses the fuel nozzles. Note that in ultra modern combustors, the diluation holes no longer exist and a much larger fraction of air enters at the fuel nozzle location.

Torque is transferred from the HPT to the HPC through the spool arms (basically a shaft), which is what connects each rotor to each other. I have highlighted this in red in the image below. The full spool is created in multiple ways. Some of the HPC rotors are forged together into sub-spools. Some of these sub-spools are welded together (becoming more common) and then some joints are done with bolts. In the second image below, is the HPC spool for the CFM56, I have circled the bolted connections. Bolts are generally used when there is a change in materials so welding can't be done. The first couple of stages will be Ti, while the later stages are a Nickle based super(ish) alloy. The HPT rotor is a Nickle based super alloy but is generally being pushed to the limit too much to be welded. When it is all put together, you have a very stiff shaft.

 (Source PDF)
The stators are attached to the outer casing. Generally there is a circumferential slot in the case, the stators slide into this slot. Generally the stators are brazed together in multi-vane assembles to reduce air leakage. There is also a labyrinth seal on the ID of each stator to reduce air leakage.
The S1 and S2 HPC rotors (your location 2) have a larger ID than the other rotors so they can fit over the bearing race when they are unbolted from the spool and to allow tool access to the bolts. The S3 rotor is the largest because it support the arm going to the bearing, a still largish blade and the bolted joint of the spool join. As you go aft the rotors get a little smaller because they support smaller blades, but that is counter acted by raising temperatures that reduce the material capabilities.
Overall engine assembly (Youtube Video of GEnx-2B being assembled). Depending on the engine it'll be assembled from Fan back or LPT forward. So from LPT forward (Very simplified). First take the built up LPT module and attach the LP shaft (aka fan shaft/fan mid shaft). Next, you would build up the HP section including outer casing seperately, then slide this onto the LPT, attach the HPT outer casing to the LPT case with an excessive number of bolts, if there is a mid turbine frame it would be installed between the two turbines with bolted joints on both sides. Then you install the fan frame to the HPC case and then the fan spool to in the LP shaft and the fan case to the fan frame. With the right tools, it all slides together pretty easily. One way the LP shaft is connected to the LPT and Fan Spool through splined connections and a large coupling nut is installed on each end of the shaft to prevent the splines from backing off. Sometimes the shaft is bolted directly to the LPT or Fan spool directly.
Sorry for being so long winded, but I hope that answers your questions.
Here is one more flow diagram for reference (source):

Wow :-) You've got great educational skills for explaining complex things with simplicity. Each word you use serves a purpose. It took me more than an hour to go through your post, not counting the thesis that is for later :-) It really deserves many upvotes, With its countless relevant details and accurate references (great pictures too), it's one of the best I've read and one I've most learned from. Many thanks for your time.

@mins, thank you for the kind words, I am glad you found it useful.

@mins, I added a youtube link above that shows the build-up of a GEnx engine, although it runs pretty quick it gives you and idea of how it all works. I also found this https://www.youtube.com/watch?v=zy4A-z2WKhw, it is mega GE propaganda but does a decent job of going through the different components and shows how different things look up close, including the stator/case attachments.


text:
Still using knots, nautical miles, inches of Hg. Is that impossible to switch to SI units?

Why doesn't the aviation industry use SI units?.

I believe only a few countries use meters and other SI units in air transportation, including India and China (please correct if wrong).
Using kts and NM in navy -- built from the length of the 1' arc on a meridian -- simplified nautical mental arithmetic, and likely also helped at the beginning of aviation.
Current ICAO recommendations
In Annex 5 - Units of Measurement to be Used in Air and Ground Operations, ICAO allows 3 non-SI units (knot, foot, nautical mile) to be used...

as alternative units because of their widespread use and to avoid
  potential safety problems which could result from the lack of
  international coordination concerning the termination of their use.

... but overall states in the same document that only SI units should be used, the same units for all members. Nevertheless the termination dates for alternative units have not been specified:

It is intended that the use of the non-SI alternative units [...]
  will eventually be discontinued in accordance with individual unit
  termination dates established by the Council. Termination dates, when
  established, will be given in Chapter 4.

Case of vertical measurements / altitude
Vertical measurement in meters may be the more complex due to the existence of flight levels in feet, with the full system of vertical separation based on FL.
This topic was discussed in Using feet vs meters for altitude?. The current question is not a duplicate of the latter.
Other non-SI units
Other non-SI measurements seem more easy to remove:

Horizontal distances in feet and nautical miles may be expressed in meters, as already done for runway lengths. It is not as important as it was to mentally translate a latitude offset in NM.
Atmospheric pressure expressed in Hg column height may be expressed in Pascal. Many pressure instruments can be already calibrated both in inHg and hPa.
Speeds expressed in knots (sometime in statute miles per hour) may be expressed in km/h.

Question
Wouldn't it be useful (and safer) in the long term if we could remove most of the imperial units from new aircraft instrumentation, procedures, ATC, documentation and maps (at least for anything other than altitudes)
Just asking what is the current view from the air transport community itself.

@falstro: Yep, didn't see it before posting. However the discussion may go further. FL in feet may make sense, but what about NM, kts, Hg inches, etc?

What benefit is there to using SI? Aviation is self-contained to a significant degree, so I don't think there's a significant cost of unit conversion anywhere in the system. Any advantage would have to be pretty significant to overcome the safety issues of switching systems.

@mins the referenced question mentions ICAO Annex 5 which should give some insight I think

@falstro: Not really. Annex 5. The document says the use of non-SI units is temporary accepted, but intended to have an end.

Things like the 60:1 rule would then become the 60:1.852 rule (or the 15,000:463 rule if you made them whole numbers, equally bad). So to find my lead radial on a 15nm arc, at 250kts it would then be, 27.78x/1.852=60 = 15x=60 = 4,  and then 4.63/1.852 = 2.5, so then 4*2.5= 10.  10 rads. Using NM I can do the calculation in my head in about 10 seconds. Yeah... no thanks.  As you said, using NM makes aviation calculations easy and there is no reason to change it.

http://aviation.stackexchange.com/questions/2572/why-doesnt-the-aviation-industry-use-si-units

In light of that question, this one is definitely a dupe.

@reirab: I agree, no argument.

Different areas of interest like to use units that help make the task at hand easier.  For example, metric was invented to make the boiling point of water 100deg, MeV/c^2 is a great way at examining subatomic particles due to their mass energy, and knoticle miles are great for navigating the planet because they are equal to 1' arc on a meridian

@SpongeBob: This leads to a funny question: When we have traveled 1' along the Greenwich meridian, we have traveled 1 NM... Is that correct for any position of Earth related to Sun and Moon? Ships and even aircraft are not bothered by the answer, but this show the confusion potentially introduced by the unit. That said I agree with your comment, though I'm rather confused by the reasons that make jewelers using "18-carat gold" instead of "75% gold alloy". Or are they trying to confuse customers, suggesting this may be pure gold?

For me metric or imperial is not the question, from my perspective the key is standardization. Having 2 different unit systems has only got drawbacks:

Customers: many airline's customers are living in a metric system, and they do not know what's is a mile or a feet. Is a matter of making flights more comfortable.
Cost reduction: units transformation is finally a cost. Engineer at manufacturers and airlines need to spend some time using a calculator to understand what is meant by other unit system. Maybe is only 30 minutes per month, but if we are talking about 2000 people, we are reaching a cost that is not adding value of 1000h per month. Finally this cost is somehow appearing in our airplane tickets.
Reduce human factor: we all are humans and exposed to errors. The less opportunity we have to make an error the best. Already there had been an issue with satellites with unit conversion. Reducing this difficulty is finally improving the safety of the air transport.
Increase competence in the sector: suppliers from, let's say, metric system have an slight competitive disadvantage when competing for a contract with imperial units. The more competition in airline services, airplane manufacturers suppliers, handling services the lower the price of our tickets.

Having 2 standards is a cost that is not producing any value and is actually a sector issue, moreover, a society issue. From my point of view the industry should try to move to a single standard. Metric or Imperial, I don't mind.
Next discussion will be which side of the road we should drive...

"The wonderful thing about standards is that there are so many of them to choose from!"

When you say "airline customers" do you mean the airlines who are customers of the aircraft manufacturers or the passengers who are customers of the airlines? If it's the former, I would strongly disagree with your assertion that many of them don't know what a foot or a nautical mile is. I would say all of them, outside of perhaps a few domestic Russian and Chinese are very familiar with both. If you're talking about the passengers, who cares? The passengers don't communicate with ATC (hopefully not, at least.) In-flight entertainment systems can and do display both systems of units.

I was referring to the passengers, professionals shall be familiar with them. Passengers are intereacting with units with communications from pilots, flight entertainment or websites. I remember the website of an airline which I connected to, where everything was in imperial, so I was not able to calculate the distance directly.

Using inHg to calibrate a barometer / an altimeter looks broken science, and adds to profane and professional confusion. Many European countries have required years ago that all weather reports use Pa and not cm/in Hg or mbar for atmospheric pressure. This was not a big challenge. That avoided headaches to understand if we were talking about Hg mass or Hg weight or which section of the pipe we were using :-)


text:
Is it possible to use variable wing geometry on a fifth generation stealth fighter?
Is there any effect on the stealth features due to variable wing geometry? If not, why have such aircraft not been designed till now? Please explain the limitations using any structural principles if possible.

Possible? Probably. Useful? Maybe. Practical? Doubtful.

What about flaps?

Of course it is possible. But it does not improve the outcome.
Swing wings were a fad of the Sixties. They never fulfilled their early promises, because the actuation mechanism is heavy. Variable sweep is only justifiable when the aircraft will fly both sub- and supersonically for extended periods. It turned out that the part of most missions which is spent at supersonic speeds is a lot smaller than anticipated in the Sixties. Just take the Rockwell B-1: Designed for supersonic penetration (B-1A) it became a subsonic low-level terrain following strike aircraft (B-1B).
For stealth, edge alignment is an important design principle. Making wing sweep variable is to throw this overboard, compromising the whole strategy of stealth. Also, the best stealthiness is only possible in subsonic flight - airframe heating at supersonic speed will broadcast the aircraft's presence to everyone with a low-cost infrared sensor.

I think the basic idea currently is to make a plane either invisible or so fast that it doesn't matter whether you see it or not, because you can't do anything about it.

@JörgWMittag: The speed route worked in the Sixties, but has since then proven to be too expensive. Surface-to-air missiles are now too powerful to make this viable. Better switch to a low earth orbit instead.

Swing wings “a fad of the 60s” - very true.  Whatever performance gains were available never justified the gain in weight.

@CarloFelicione: Absolutely! They did offer performance gains, namely the ability to fly Mach 2+ while still having acceptable field length, but it turned out that this particular performance gain was useless in real life.

@JörgWMittag - that is not entirely true any more. The F-22 is designed specifically to have a range/speed/altitude envelope that puts it outside the S-300 and S-400 engagement envelope. One complaint about the F-35 is that it is not fast enough in this regard and will spend enough time within the detection range that they can't safely approach them.


text:
What does "out of trim" mean?
Our flight was delayed from takeoff because the captain reported it to be "out of trim". What does this mean?

Did you notice people being shifted to different seats during the delay?  For center of gravity purposes, the cabin is divided into zones.  It's possible that the actual assigned seats filled left one or more zones "underweight" you might say, due to ppl not showing up.  If this was the case you'd have seen the Flight Atts requesting people to move to different seats.

In this context, it would mean the aircraft is loaded in such a way that the Center of Gravity is too far forward or aft.  That's actually not the way we usually use the word "trim" in aviation but it's what it means in this case.

How is this detected on the ground? are there dedicated sensors or a system for that?

@Alex: That sounds like a great candidate for posting a new question.

@Alex: they know a lot about the baggage, and they know where the passengers sit.  That's why they will move passengers around.  If you fly on a small enough plane, they will ask you your weight (it's happened to me twice, though once was a large passenger helicopter).

https://aviation.stackexchange.com/questions/1850/do-some-airplanes-have-weighing-scales-on-the-landing-gear?noredirect=1&lq=1

"Trim" is the ability to correct for deviations in flight controls by prepositioning the flight surfaces for a particular direction. For example, if the aircraft is pitching up a bit by default, you can trim down in order to counteract it.
"Out of trim" would mean that the Aircraft has either been improperly trimmed, or is operating outside of the range trim can be applied. (If the aircraft is pulling down hard, you can only trim up so much.) This can be due to a mechanical defect, improper weight and balance, or other issues. He may not be able to safely guarantee the aircraft is trimmed in such conditions.
There is a related question here that explains it in further detail:
What is an out-of-trim condition and how is it detected?

This can, however, only be detected when flying. On the ground, “out of trim” means balance out of limits.

Trim controls speed.  The airplane will seek, in the absence of a pilot elevator input, a given speed based on where the trim device, tab or moveable stabilizer, is set.  If an airplane is pitching up as in your example,it means it's going faster than its trim speed and is trying to slow down to achieve equilibrium.  When you adjust the trim nose down to stop a pitch movement, you are increasing the airplane's trim speed to match its current speed.

If the center of gravity was out of limits it is unlikely the crew would use the term "trim" to describe it.  Also, if passengers needed to be moved to correct the condition you would see this happening.
More likely the fuel control unit was out of trim and needed to be adjusted.  It is a fairly common procedure if an engine parameter is a little bit off from normal.
From Flight-Mechanic.com:

The field repair of the turbine engine fuel control is very limited. The only repairs permitted in the field are the replacement of the control and adjustments afterwards. These adjustments are limited to the idle rpm and the maximum speed adjustment, commonly called trimming the engine. Both adjustments are made in the normal range of operation. During engine trimming, the fuel control is checked for idle rpm, maximum rpm, acceleration, and deceleration. The procedures used to check the fuel control vary depending on the aircraft and engine installation.
The engine is trimmed in accordance with the procedures in the maintenance or overhaul manual for a particular engine. In general, the procedure consists of obtaining the ambient air temperature and the field barometric pressure (not sea level) immediately preceding the trimming of the engine. Care must be taken to obtain a true temperature reading comparable to that of the air that enters the engine. Using these readings, the desired turbine discharge pressure or EPR (engine pressure ratio) reading is computed from charts published in the maintenance manual.

Interesting. I know little about jet engines so you may be right.

It would be ironic if my top-voted answer ever (and only a few days old!) were wrong, while all my answers about the relationship between thrust, lift, and climb angle, which are correct, are showing an average vote score around zero. I don't think it's really true that the best answers rise to the top at Aviation SE!

Ironic indeed!  It is a well crafted answer though.  Hard to know the credentials of those answering and voting here...

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


text:
What are RNP and ANP in area navigation?
What are Required Navigation Performance (RNP) and Actual Navigation Performance (ANP)?

Possible duplicate of What is the difference between RNAV and RNP?

Although ANP is briefly mentioned in that answer, it's not completely clear what ANP actually is.  I'll provide a good answer here, but if we would prefer to edit that other q/a, that's ok too.

@Jimmy As the author of the 'other' answer, I'm OK with leaving this open. It is a different question and my reference to ANP did not explain the concept of how ANP is estimated.

RNP is a numerical value that refers to the level of performance required for a specific published procedure.  If the procedure has an RNP 10, then the on-board navigation equipment must be able to calculate its position to within 10 nautical miles. If the procedure has an RNP 0.3, than the equipment must be able to calculate its position to .3nm.
ANP is the "actual" level of performance being experienced real-time. The on-board navigation equipment estimates the quality of the reception and determines how "reliable" it thinks its own position is.  If the estimate of reliability is high, then the ANP is lower.  An ANP value of 0.6 indicates that the navigation equipment is confident of its own actual position to within .6nm.  Essentially, this means that if the equipment puts a point on the map of where it thinks it is, there is a circle around that point with a .6nm radius and the aircraft is somewhere within that circle.
If the RNP required value is lower than the ANP value, you cannot use that procedure.  If you're using a procedure, you must monitor the ANP value. If, at any time, the ANP goes above the RNP, you must exit the procedure.
Here is an image of a Boeing 737 FMC displaying the current ANP (.06) and the RNP (2.0).  Courtesy of http://www.b737.org.uk


text:
Can I take my Canadian PPL with flight hours logged in the US?
I was wondering if I can combine my flight training hours in the US with my Canadian ones if I want to take my PPL in Canada?

This is a little excerpt from a Canadian document, as it relates to the conversion of licences back and forth between the two countries.

The Agreement provides, in pertinent part, that the FAA and TCCA will pursue mutual cooperation in the evaluation and acceptance of each other’s systems and standards in the issuance of certificates and licences.

Keep in mind, this text is for conversion after you already have a full license, but I believe each country recognizes the hours in a log book from the other. Best bet would be to call or email the flight schools in the area you plan on going, and get the official word on it.
Edit: I should have put this here in the first place, but here is the link to the Conversion agreement between U.S. and Canada. You will find the snippet that I pasted in the 'Purpose and Scope' section.

could you provide a link to said "Canadian document"?


text:
Where can I find runway usage statistics of USA airports?
Ok I’m looking for stats and data of planes arriving at various airports and what runways they use most. I need to know the most used runways for arrivals in airports here in the States. Can anyone point me in a direction where I can easily find this info?

One can also review the data provided by the airlines at the big airports. For example, Boston-Logan has data by month of the year going back to 1999.

The statistics included below are compiled by Massport from information provided by the airlines.

You won't find data for the 5,000+ non-towered that is much different than what airnav.com reports.  My home airport's "operations center" where we pay for gas & stuff is mostly not-manned, and for certain not between ~4PM and 8 or 9AM. I've left plenty of time before 8 and after 5 with no one to see me come & go. And if I didn't buy fuel, they'd have no record of my plane having moved at all.
Have tried the FAA's Aviation Data & Statistics page?

Like @CrossRoads said in his answer, there is no data available on which runways are used most. You will need to listen to LiveATC on several days and keep track of the winds to get a rough estimate. For example, from listening to the tower at KSFO I gather that they usually land on 1L and 1R and take off on 10L and 10R. However, when the winds are too strong out of the east they use 10L and 10R for landing.
Likewise, if you listen to the tower at KJFK you can tell which runways are in use on any given day. There appears to be more variability there because the winds are much less consistent.
And then there are airports like KOAK and KSJC that have one runway or set of runways that GA aircraft use and one for the big guys.
The airports might keep that kind of information so a call to a few of them might give you some answers, but I am not aware of it being published anywhere.

SFO rarely lands on 1L/1R (it's an impressive circling approach used if winds truly demand it, which isn't often at all). Normal flow (used ~83% of the time) has landings on 28L/R and departures on the perpendicular 1L/R (except for aircraft that need full length departures on the 28s). An alternate plan is used at night, winds permitting, for noise abatement.

@ZachLipton I remember reading about some 1L/1R landings and how difficult they are, but I can’t find them at the moment. I think there were some neighborhood complaints as well since they come in low over residential neighborhoods.

FlightAware.com can compile runway usage information, based on flight track positions near the airport.  Please reach out if you're still interested in this: https://flightaware.com/commercial/customreports/


text:
When is aileron trim used?
There is an aileron trimmer in some Boeings. When and why should it be used?
P.S. I'm not a pilot, can you answer with less smart words?

Given your request to "answer with less smart words," it's hard to know what knowledge can be assumed, but I'll give it a try.
Let's say you're hand-flying the airplane straight and level, and you find that the right wing keeps wanting to drop, which you prevent by using left-aileron pressure on the control yoke. You can "trim out" the need for that left aileron pressure by rotating the aileron trim to the left (counter-clockwise).
Aileron trim is not often used for the simple reason that in normal aircraft operation, it's usually set where it should be from the previous flight.  In other words, you don't fuss with it unless you notice a need to fuss with it. In 12 years on 727s and 747s, I think I used aileron trim less than a dozen times.
The reasons that I can think of offhand that would make you want to fuss with it include:

The trim wheel was inadvertently moved (or deliberately as a bit of a prank) by someone.
A fuel imbalance has occurred between the fuel in the left and right wings.
You're doing a 3-engine ferry on the 747 or continuing a flight after having lost an engine.

To the best of my knowledge, all Boeing aircraft have aileron trim capability, not just some. Indeed, I would be surprised to find any transport category aircraft that does not have aileron trim capability.
Essentially, aileron trim can be used to to keep and airplane from responding to a situation where one side of an airplane is significantly heavier than the other side.

Another main one is with most jets the wings are often not perfectly straight after coming out of the jig.  Variations in riveting sequence can apply torsion forces that are relaxed when out of the jig and the wing box twists ever so slightly.  This may show up in flight, and the manufacturer will try to rig ailerons and flaps to counteract it, within the rigging tolerances of the surfaces.  Sometimes that is not quite enough and a tweak of aileron trim is required. The OEM will usually have a quality control based limit on the amount of trim required to stop a roll for a new delivery.

Does a single engine failure usually require aileron trim? Seems like you'd have to counter the asymmetric thrust with rudder trim and counter the rudder roll with aileron.

@TomMcW I think your comment would make a good regular question. I was never particularly good at aerodynamic theory, and the almost 20 years that have passed since I retired and my increasing dementia have made me unable to answer that with confidence. What I seem to remember from multi-engine training and the two real-life engine failures I had where we returned for engine-out landings, was that we didn't fuss with aileron trim, but I'm fairly sure we did when doing two 3-engine ferries and a continued flight after an engine failure in the 747.

Pilots playing pranks on each other can turn out bad. I read about a flight that crashed because during flight, while the captain was in the bathroom, a pilot in the jumpeat engaged the rudder gust lock as a prank

@TomMcW I very much agree, but that's a no-brainer for me as I'm not a prankster. When I was flying the F-27, we had a big, 300 lb senior captain who, when deadheading, would walk up and down the aisle, forcing those flying to re-trim. He was also known for leaving a fake but very realistic looking pile of fecal matter on seats.

In short almost NEVER.
I have flown the A320/A330/A340 and they don’t have an option to trim the ailerons.
I am currently flying the 777, and when you feel that the aircraft is not flying straight we generally tend to use the rudder trim over the aileron trim.

Aileron trim is used in case of wings fuel assymetry, this is used until you correct the assymetry by providing the engines from a single wing.

This doesn't really add anything to existing answers.


text:
What kind of work you can get with a private pilot licence?
I´m planning to be a pilot, i just want to know if you can work only with the private licence and where.

As a private license doesn't allow for commercial activities in many countries, maybe you need to rephrase the question into "Are there countries where a commercial activity can be conducted with a private license?"

You cannot do so.  A private pilot’s license - at least in the US - prohibits you from offering airman services for compensation or hire.
If you intend to fly professionally, you will need at least a commercial pilot’s certificate.  An instrument rating is also highly recommended as is multi engine class ratings for the greatest chances of employment.  Air carrier operation will require you to hold an airline transport pilot’s license for part 121 operations.

On the other hand, would a PPL prevent someone from getting a job even in commercial aviation? I could imagine that having a PPL could be a small advantage, all other things equal, for example to become a cabin attendant, since some (all?) medical requirements would already be taken care of. Of course, all other things are never equal.

Note that the last part about air carrier operations only apply to USA. In most other places, only the captain needs ATPL and one can be F/O with just CPL (and instrument rating and appropriate type rating).

I'm not an aviation lawyer, or that familiar with current regulations, but I think you can fly if it's only incidental to the work.  For instance, I used to do work at sites hundreds of miles distant from the business location, and often would fly myself there, rather than driving or taking commercial transport.

You can fly ‘in furtherance of a business’ ie if you fly an airplane for business travel or to aid a business.  But you cannot be paid for the flying ie for compensation or hire.

This is defined under §61.113 PPL Privelages and Limitations.

The opportunities are limited, as the FAA pretty loosely construes compensation.  For example, you cannot fly to take photographs, which you sell.
You can conduct operations which are incidental to your work. For example, if your business required you to be in different locations, you may be able to fly to those locations, similarly to driving there.  I do not believe that you could haul product or customers.  If you are considering this type of work you should consult an aviation attorney.  I would search the FAA Letters of Interpretation (LOI) first before spending money on an attorney.
There are some other things you can do, as a private pilot.  For example, I have an uncle who is a farmer, and conducts Part 137 ag operations on his farm.  Sometimes he hires other pilots, and they need commercial licenses. However, he can apply chemicals to HIS farm land without a commercial.
In general, having a private pilot license may help show a level of experience which may help you acquire non-flying jobs, but  I suspect you are not interested in that.
The entry point for most pilots is commercial/instrument/cfi, however I have known a few pilots who had just commercial/instrument, who built hours towing banners, towing gliders, flying jumpers and as SIC for 135 operations. Some, who are good at networking, may get jobs flying for Part 91 corporate ops, but with low hours, the insurance requirements are steep. Building hours is the primary reason why many pilots get an instructor rating. That motivation may not assure the best instructors, but that is how the industry is currently structured.


text:
Why is it not allowed to dispatch an Airbus A320 with an inoperative ELAC 2?
In the case of ELAC 2 failure, ELAC 1 will take over. However, it is not allowed to dispatch an Airbus A320 with an inoperative ELAC 2. Why is that?

Is it permissible to dispatch with ELAC 1 inoperative?

@CptReynolds According to the MMEL, ELAC 1 may be dispatched inop with conditions, but there is no relief for ELAC 2.

@user71659 If ELAC 2 is inoperative, could it be allowed to swap ELACs and dispatch under MEL with ELAC 1 inoperative? That would explain why ELAC 2 inoperative doesn’t have an MEL relief.

As pointed out by this discussion on PPRune, ELAC 1 only controls elevator actuators hooked in to the Blue hydraulic system. ELAC 2 is split across Green and Yellow.
If ELAC 1 is the only operational computer and the aircraft enters emergency electrical configuration, blue hydraulics will be lost until the RAT deploys. Further, the fallback for ELAC 2 (G/Y hyd) is SEC 2, which is not powered in EEC. Thus, the aircraft will have no primary pitch control.
The solution is that if the fault is in the ELAC computers themselves, to swap the units before dispatch.
In general, if there's something weirdly asymmetric about the A320, the first guess should be something to do with EEC. This is because EEC, by design, tries to only power one unit, typically number 1, of each system.

Basically during RAT extension blue hydraulic system is not powered which operates blue ACTR of elevator which is controlled by ELAC#1. To avoid control confusion ELAC#2 straight away given as no go to give pitch control during this transit RAT extension phase.


text:
How does thrust reverser selection have a destabilising effect on the rudder and increase the lateral skidding tendency of the aircraft?
I was reading in the FCTM landing section normal procedures the below paragraph.

The reversers have a destabilizing effect on the airflow around the
  rudder and thus decrease the efficiency of the rudder. Furthermore
  they create a side force, in case of a remaining crab angle, which
  increases the lateral skidding tendency of the aircraft.

Could someone please explain as to how this effects airflow over the rudder and increase the lateral skidding tendency of the aircraft?

I don't have time to write a proper answer now, but tf there is a crab angle, the reverse trust is not aligned with the runway centerline. This angle causes the a sideways component of the thrust.

Interesting reading about rudder blanking on the MD80. Runway Excursion During Landing
Delta Air Lines Flight 1086
Boeing MD
88, N909DL
New York, New York
March 5, 2015 https://www.ntsb.gov/investigations/AccidentReports/Reports/AAR1602.pdf

This is called rudder blanking. While I was searching for it, I came across this image

(Source)
As the Skybrary article mentions

Rudder blanking is a particular risk to aircraft with rear mounted engines and "T" tails.

I emphasized the word particular since I perceive it as an indication that it's a risk for other planes as well without rear mounted engines.
Now the flow from trust reversers, disturbs the airflow around the rudder reducing its effectiveness. In strong crosswind you rely on rudder to keep the aircraft centered on the runway. If you apply thrust reversers right after touchdown, you reduce the effectiveness of the rudder and in turn it might reduce the crab angle making it harder to keep the aircraft centered.
Addendum
I will try to explain with a graphic, though as I've already stated in my comment, I'm not an expert.
As you can see in this image taken from Wikipedia, the thrust reverser output is not blocked by the wing, so it's quite safe to assume there is a jet similar to the first image.

I would estimate that the area of that vertical jet is more or less contained in the red circle seen in the next image. The free stream will push the turbulent jet from the reverser towards the back (as you can see in the first picture) and disturb the flow around the fin. The orange area is parallel to the free stream and shows the direction of the turbulent flow which might not be exactly the same in reality as the fluid particles have a tendency not to follow straight lines.
The plane is rotated 15 degrees to simulate a moderate "crab angle". From the picture posted in GdD's answer, you can assume this can be more if the vertical wind component is high enough.

(Source of original image)
Now one thing you might need to consider is that the engines of a wing mounted engine plane have significantly more distance from the vertical stabilizer compared to the tail mounted engine plane. That distance might be able to weaken the effect of the stream, enough to not cause accidents like this mentioned by Sports Racer in his comment. But that doesn't mean the problem is not there, hence the warning from Airbus.

any reference for if rudder blanking affects wing mounted engines as I can't find any ?

@Jai No unfortunately not; only my remark about particular in Skybrary that gives a hint about it. I could try to explain with a schematic, though it's not possible now and I'm not an aerodynamicist so I don't know if that would be accurate enough.

@Jai attempted to explain; hope it helps

your answer is correct I confirmed this with my company thank you for going through the effort also.

On a crosswind approach many pilots use the rudder to yaw into the direction of the wind in order to remain on centerline, which is what's called crabbing. In the picture below you can see that the aircraft is yawed (i.e. crabbing) to the right. The difference between the centerline and the airplane's heading is called the crab angle.

If a pilot maintains the crab to touchdown, which is a common technique, the aircraft will have a residual crab angle, like this.

If the pilot were to deploy reversers in this situation there will be a significant sideways force in the opposite direction of the crab, in the case of the picture towards the right, which could cause the airplane to skid in that direction.

could you explain what is this sideways force? Also how does it have a destabilizing effect of the airflow over the rudder?

@GdD consider the relative airflow in your above picture, and you'll see that you don't have any sideslip angle. This means no rudder is required to "remain on centerline" as long as you have an appropriate crab angle. The rudder is not really used until when you wish to decrab (just before or after touchdown, depending on aircraft and environmental conditions).

I'm not attempting to answer the rudder part of the question @Waked, just the side component to the thrust reversing.

@GdD I do understand that, and I do not mean to nitpick, but I thought I'd let you know, as you still might want your entire answer to be factually correct.

I'm happy to refine it when I have some time @Waked, what is it you don't understand?

@GdD could you please help explain this sideways force?

"in the case of the picture towards the right" - Towards the right side of the picture or the right side of the plane? Those are opposite directions and I'm not sure which one you mean.

Good question @TannerSwett, I mean to the right as in the airplane's frame of reference, which is left on the picture.


text:
How does the LIP package which is standard on the A320NEO enable to approach at a slower speed?
Could someone kindly explain as to how the lift improvement package on the A320NEO enable it to approach at a slower speed compared to the IAE CEO. I have the list of the modifications which is done but it doesn’t explain how it helps.
They are:

Slats (de icing slay/track shutter modifications and stiffened slat/track seals)
Slat 1 enlarged horn
Adding an outboard nacelle strake
Fuselage wing fairing root fillet aerodynamic improvement
Wind shroud close to flap 1 and 2 junction
Introduce extended trailing edges on spoilers 1 and 2 and on fixed wing box trailing edge between spoilers 1 and 2.

These modifications mainly allow the aircraft to approach up to 5 knots slower than our CEOs. But how exactly do the modifications work in reducing the approach speed?

This question would benefit a lot from images that show the modifications.

On first impressions, all of those (except the nacelle strake and the fillet) seem to modify the high lift system (slats/flaps), presumably to optimise air flow in the gaps between slat and main wing or main wing and flaps. This is probably done to increase the maximum attainable angle of attack or lift coefficient, which will reduce stall speed and thus allow a lower approach speed.
The nacelle strakes normally are used to optimise flow around the engine nacelle at high angles of attack, either to prevent premature wing stall around the nacelle or to at least improve aircraft handling qualities by preventing localised flow separation at the nacelle. Adding another strake on the other side will, I imagine, again allow a slightly higher angle of attack to be sustained and thus will lower the permitted approach speed.
The wing body fairing modification most probably, too, will allow a more optimal local air flow.
All of this is my speculation based on the list of changes in the question; I don’t have additional knowledge on this particular aircraft performance package.


text:
Why should you never squawk 0000 in the USA?
FAA Order 7110.66E says

Code "0000" should never be assigned or used.

and

Code 0000 must never be assigned

However, NASA recommends that crews set 0000 after landing to help detect when a clearance has not been received.

Resetting the transponder to 0000 (four zeros) after landing can help you, or the next crew, detect lack of a PDC. Additionally, should a flight depart without setting an appropriate IFR code on the transponder, ATC will be more likely to quickly detect the problem. (Setting 1200 on the transponder may lead a controller to believe the target is normal VFR traffic.)

The idea is to set a code that could never be correct. If you set 0000, a casual glance at the transponder will indicate "Some part of our preflight did not get accomplished" rather than "Ah the other guy must have set our code already".
I set my transponder to 1200 after IFR flights, and am considering changing to follow NASA's recommendation of 0000 instead, but I don't want to create headaches for ATC if they see it one day on their scope.
Why should you never squawk 0000 in the USA?

“Ah the other guy must have set our code already".  I cannot fathom anyone actually making such a reckless assumption.  Because I would automatically think “ah the other guy must have forgotten to squawk 1200 after landing...” Sure, 0000 would add another layer of cheese to Reason’s model, but is IFR traffic taking off with a 1200 squawk (inadvertent VFR?!) really a problem deserving of such (forbidden) mitigation?  If you fly for a carrier that swaps crews you will likely have it in your SOP to always file IFR, in which case resetting 1200 works fine.

@MichaelHall  In this case, "the other guy" is the other pilot on the same crew, not the previous pilot who has now left the aircraft.  Setting 1200 could work the same as setting all 0's, either conveys "you haven't set your assigned code here yet," but turning all 4 dials counterclockwise to the stops is more certain than dialing in 1200.

@RalphJ, did you clarify with Steve on the side that that’s what he meant?  Because if so, with a two person crew it ought to be even more easy to avoid taking off with the wrong squawk set, right?  Anyway, most newer digital ADSB compliant transponders I have seen use a single “VFR” button to roll in 1200 with a single push, making it very easy to be certain you aren’t IFR any more.

@MichaelHall - Although Ralph did not clarify with me, that interpretation is correct.  "The other guy" is intended to mean the other pilot on the same crew.

@MichaelHall  Transponders in airliners have no such VFR button (we never fly VFR, and if we did we'd still get flight following), and the control heads in them aren't all that new.

@RalphJ, C208 Caravan airliners have them…. ;). Anyway, if you think quad zeros is better than 1200 then have at it, I just don’t see a clear benefit.

Anyway, the “other guy” argument is a moot point. Either 1200 or 0000 will prevent you from taking off without a valid IFR squawk, or from presuming that either your or the other crew had already set it.


text:
Airbus control architecture - where does the actual autopilot live?
I'd like to ask for confirmation about the A320 (and, generally, Airbus family) control architecture. The book Aircraft Systems provides the following
overview of A3XX computing architectures:

Focusing particularly on the A320 family, are the ELACs and SECs merely actuator controllers for the control surfaces, or do they also carry the autopilot flight control algorithms? Or is the "autopilot" a separate entity, which feeds desired control surface positions to the ELACs and SECs (i.e. these latter are simply "slaves" to the autopilot)?
This picture from an A320 Operating Manual makes it seem that ELACs and SECs are autopilots themselves (i.e. there is no separate entity that is the autopilot that feeds them signals):

However, the same manual has another figure which makes it seems that indeed there is a separate autopilot entity:

If the autopilot is indeed a separate "master" entity which feeds desired
control surface position signals to the ELACs and SECs, is this a concept that generalizes to the rest of the Airbus family? Where does the autopilot software then live?

Short answer: Autopilot is a feature of the Flight Management And Guidance System (FMGS), and in particular each of the two Flight Management And Guidance computers (FMGC) manage its autopilot.

Are the ELACs and SECs merely actuator controllers for the control
  surfaces?

Correct, but they are reconfigurable in case of failure of one of the SEC, ELAC or FAC. In addition the ELACs are used to detect the excursion off the flight enveloppe (e.g. alpha prot). They inform the FMGC of such situations.

It seem that ELACs and SECs are autopilots themselves

No, AP is a separate function of the FMGC (and of the FAC).

FAC, ELAC, SEC are flight control computers, but are not equal.

FAC (Flight Augmentation Computer) in particular is devoted primarily to rudder control, and all the associated functions (e.g. yaw damper). It is a main component of the autoflight system.
Ailerons and elevators are directly controlled by the Flight Management and Guidance System (FMGS), which includes the autopilot.

Autoflight system presentation by Airbus:

The auto flight system (AFS) installed on the aircraft is made up of
  two types of computers :

the flight management and guidance computer (FMGC)
the flight augmentation computer (FAC)

and two types of control units :

the flight control unit (FCU)
the multipurpose control and display units (MCDU).

The functions of the FMGC are :

autopilot (AP)
flight director (FD)
automatic thrust control (A/THR)
flight management.

The functions of the FAC are:

yaw damper
rudder trim
rudder travel limiting
calculation of the characteristic speeds and flight envelope monitoring
acquisition of the yaw AP order.

Redundant FMGS are divided in two functions: Command (issue commands to flight controllers) and Monitor (monitor the result of the commands, e.g. by analyzing air data and inertial data to detect anomalies).
The FMGS has different functions:

It uses the navigation database containing aerodromes, waypoints, navaids, procedures, etc, for the routing of the aircraft.
It takes into account aircraft performance data to manage the vertical aspects of the route.
It controls navaid receivers (VOR, DME, ILS, etc) and use navigational data.
It receives air data (from pitot, static pressure sensor, pitch angle probe) and inertial data.
It monitors the progress of the aircraft on the route programmed into the flight plan.
It issues flight guidance cues using the flight director indicators on the PFD.
It takes into account short term instructions entered by the crew using the FCU, and long term instructions entered using the MCDU.
It manages flight control laws and laws reconfiguration after controls failures.
It is coordinated with the Autothrust system which, with the FADEC, control fuel flow and engine thrust (FMGC is interfaced with ECUs/EECs).

The manual way of controlling the aircraft is:

FMGC gives instructions to the crew using the flight director cues and the yaw cue.
The pilot follows the cues with the controls (rudder pedals, side stick)
Pilot commands are taken into account by the flight control computers (FAC, SEC, ELAC) which determine the way control surfaces will be moved, possibly limiting the deflection ordered by the pilot to maintain the aircraft within its flight envelope.
FAC, SEC and ELAC orders are sent to respective actuator controllers.
Two notes on this transmission:

There is a final control function on the actuator, to allow actuator redundancy for control surfaces, e.g. for elevators:

Each servojack has three control modes: Active: The jack position is
  electrically-controlled, Damping: The jack follows surface movement,
  Centering: The jack is hydraulically retained in the neutral position. (Source)

ELAC, SEC and FAC can be reconfigured according to law degradation status, the outputs of these FCC can be sent to different actuators, so the electrical circuit between an FCC output and an actuator input includes some switching circuitry.

Because of the two notes above, sending an electric order to the actuator doesn't mean the actuator will move the control surface, it depends on the current mode.
When the autopilot (AP) is engaged:

The cues displayed by the FD and yaw indicators are converted directly into orders to the flight control computers. So AP is just automating what the pilot would have done when following the cues.

While in cruise only one AP can be engaged, landing may requires the two AP for automated approach and landing.
FMGS computer location

Source of all images: A320 family ATA-22 Autoflight Maintenance.

There seems to be a small discrepancy in your and @ymb1 answers. You say "FAC, SEC and ELAC orders are sent to respective actuator controllers" while ymb1 says "ELAC is the computer that sends the commands via wires to the motors (hydraulic; electric)". So your answer makes it seem that there are further ACEs (actuator control electronics) after the ELAC/SEC while ymb1 makes it seem that the ELAC/SEC are ACEs themselves with further logic for flight envelope protection, etc.


text:
Is there a regularized width of yellow taxiway ground bands?
What is the width of the yellow stripes that are painted on the ground of the taxiway?
Is it the same on the whole taxiway or does it vary from an area to another? Is it mentioned in the aerodrome design manual issued by the international organization of civil aviation?

Hello there, welcome to Aviation.SE. Nice and interesting question!

See 5.2.8.10 in ICAO Chicago Convention annex 14 ("A taxiway centre line marking shall be at least 15 cm in width")

@kevin thanks mate :)

@mins thank you, that's what I was looking for! is there a max value to the line marking width though?

No maximum at the ICAO recommendations level, however any country may deviate from or complement ICAO, differences should be explained in AIP (GEN-1.7). To relate to Noah's answer for FAA, in USA AIP, this would be in GEN 1.7−86, but there is nothing.

In the FAA's document about standards for airport markings, it says:

e. Characteristics.
(1)
Width. The taxiway centerline marking width, which is either 6 inches (15
  cm) or 12 inches (30 cm), is based on the type of taxiing operation as described below. Uniform
  width must be maintained for the entire length of the taxiway except under the following
  conditions.
(i)
The taxiway or part of the taxiway is designated as a SMGCS taxi
  route. Under this designation, the width of the taxiway centerline must be 12 inches (30 cm)
  wide and, on light-colored pavement, further outlined in black. The taxiway centerline width of
  any remaining section of the taxiway that is not part of the designated SMGCS taxi route may
  change abruptly at that point or at the intersection with other taxiway centerline markings, for
  example, reduced from 12 inches (30 cm) to 6 inches (15 cm).

Source, chapter Taxiway Center Lines, page 43
For the taxiway edge lines, following rules apply:

e. Characteristics.
(1)
  The outermost edge of both marking schemes must be painted along the
  edge of the usable pavement.
(2)
  The continuous taxiway edge marking consists of dual, continuous lines
  with each line being at least 6 inches (15 cm) in width and spaced 6 inches (15 cm) apart (edge to edge) [...]

Source, chapter Taxiway Edge Lines, page 48

This really is a great question, I have never thought about airport markings being such a complex thing.

thanks @Noah Krasser, I guess the regulations of the international organization of civil aviation are applied in all airports of the world, is it the case for the federal aviation administration (since it is an american administration and not an international one)?

@user2651062  ICAO isn't a regulatory body per se, and it doesn't issue regulations. There are ICAO standards and recommendations, but each sovereign nation implements those as it sees fit, publishing (somewhere) whatever they do differently so that pilots can know what to expect.  Generally the FAA doesn't deviate too much from the ICAO stuff, although as the answers & comments above show, they may be somewhat different (i.e. ICAO is 15 cm or more, FAA is 15 cm (exactly) in this case, and 30 cm (exactly) in that case. Another nation might make all stripes 20 cm wide, etc).

Just because you have a standard, doesn't necessarily mean it is implemented consistently. ;-)


text:
What are the fins near the tail of a helicopter called?
My young sons are very enthusiastic about helicopters and I am repeatedly asked to name parts of their model aircraft. I would like to do so correctly, but my research has not always given definitive answers. I hope you can help.
Fixed to the tail boom and close to the tail rotor, some helicopters have a pair of horizontal fins. My research suggests these could be referred to as elevators, horizontal stabilisers, or horizontal fins. Is there one correct term, or does it depend on how they are used? Why do some helicopters not have them?
Most (all?) helicopters have a vertical fin connected to the tail boom. I have seen this labelled as a rudder or vertical fin. Does this depend on its function (moveable or fixed?) or can you suggest a better name?

You can call them horizontal and vertical stabilizers, since that is exactly what they do, in forward cruising flight.  The vertical stabilizer is there because the tail rotor itself doesn't provide as strong a weathervane effect as a fixed surface. So it stops the nose from oscillating left and right in forward flight same as the stabilizer in an airplane.
The horizontal stabilizer is to provide some down force to keep the body angle a little more level in cruise flight.  The rotor disc is flying along doing its thing with this big weight under it, which wants to swing back and pitch the nose down from air drag and the forward movement of the suspension point (more or less like running along with a tennis ball suspended on a string - it swings back and stays at an angle until you stop running).  The horizontal stabilizer's down force counteracts some of this and helps dampen pitch oscillations and keep the nose at a more desirable (higher) attitude.

OK, so following your suggestion and in the absence of any contrary views, I will use the descriptive names. Thanks for your advice.

The horizontal ones that change angle of attack during flight are called Synchronized Elevators (Sync-El). Connected to cyclic inputs to expand cg range.

You mean like the ones on the Blackhawk?


text:
What is the procedure when a required A/D inspection via an AMOC has gone overdue?
I recently purchased an aircraft that was legally (and otherwise) airworthy.  There is a visual inspection due (any private pilot can perform it) every 10 hours, but the ferry pilot may have overlooked this during the 18 hour ferry trip.  The inspection due time has now gone over the 10 hour requirement.  Are there additional requirements other than just inspecting again for compliance, or must something be submitted to the FAA as to report a non-compliance issue?

Each AD is specific (and unique) to the procedures and compliance outlined in the AD. If the AD does not say otherwise, all that is needed is to comply with it (do the inspection), and then make an entry in the maintenance log book, and you will be good to go.
I have never seen an AD that addresses circumstances when not previously complied with. For example, a Cessna 172 requires an inspection of the horizontal stabilizer spar; it does not matter if no one has done it for 45yrs. All that is needed is to do the required inspection and it is good to go :)